But after a reassessment hundreds of prescriptions were cancelled, with up to one third of patients taken off at least one drug.

Hundreds of prescriptions were stopped because they were no longer effective and dozens because the patients were experiencing side effects or drug reactions.

A further 121 patients were sent to their GP for further review, and 89 patients had their dose reduced.

The most common drugs which were stopped were the blood-thinning drugs warfarin and clopidogrel, aspirin, alendronic acid for osteoposrosis, cetirizine for hay fever and allergies, laxido for constipation, omeprazole for gastric reflux and adcal-d3, a drug to boost calcium and vitamin levels.

The research, carried out by pharmaceutical consultants Interface Clinical Services, predicted that the changes would save the NHS around £192,000 a year. However there are more than 5 million over 75s in Britain, which suggests that the cost savings across the country if everyone was similarly assessed could amount to millions.

Too many drugs raises the risk of hospital admissions for the elderly

Charities said polypharmacy – in which patients are prescribed a number of drugs – was becoming an increasing problem.

Caroline Abrahams, Charity Director at Age UK, said: “We know that the more medications you take, the greater the risks, such the risk of giddiness and of falling. This is because of what happens when ‎different drugs interact and in the worst cases older people can even end up in hospital.

“This will be an increasing problem as our population ages, with as many as three million older people expected to be regularly taking multiple medicines by 2018.

“It is therefore extremely important that it becomes routine for older people to have their medication reviewed regularly, and the more drugs they are taking the more important this is.”

Katherine Murphy, Chief Executive of The Patients Association, added: “The Patients Association has been aware for some time about the problem of patients being prescribed too many different medicines, often with one medicine being prescribed to reduce the symptoms of another.

“The lack of any regular review of a patients medication sometimes over several years, is concerning, particularly for vulnerable older people who may feel unable or are unwilling to challenge this aspect of their care.

“We welcome any initiative to improve this situation in the interests of patient safety. The research highlights that medication is often not required, may have limited benefits and can be unnecessarily expensive.”

Regular reviews could save the NHS millions of pounds

Four out of five people aged 75 or over now take at least one prescribed medication, and patients on multiple medications are more likely to suffer drug side effects and adverse reactions. Adverse reactions and side effects from drugs account for between five per cent and 17 per cent of all hospital admissions

“There is a clear and steady increase in the number of patients admitted to hospital with drug related side effects ,” said a spokesman for Interface.

“By conducting this kind of clinical assessment in primary care practices, Interface is helping to reduce drug-related adverse events in over 75s and decrease the burden that they place on secondary care services.”